so a user will register themself at abc.com but then their user will tied to a.abc.com or b.abc.com with a specific code for each subdomain?
let say a.abc.com reference no is 111; b.abc.com reference no is 222
so when a user register using the reference no 111 their user will tied to a.abc.com .
Does bubble has this feature?, If yes, please how to do it?